1. Field of the Invention
This invention relates to a manual transmission with three shafts, which makes it possible to have five forward speeds and one reverse, and which is applied particularly to motor vehicles.
2. Background of the Related Art
Numerous three-shaft manual transmissions are known, such as those with a first secondary shaft which makes it possible with the primary shaft to have a standard manual transmission with four forward speeds and one standard reverse with sliding gear, and to which is merely added a second secondary shaft, on which a fifth speed gear is placed, which is driven by the same gear of the primary shaft is the fourth speed gear.
Other types of manual transmissions are known which provide, on a first secondary shaft, the gears of first and second speeds and reverse, while the second secondary shaft has the gears of third, fourth, and fifth forward speed. In these compact structures the idling gears of the first speed and third speed are driven by the same primary gear, while the idling gears of second speed and fourth speed are driven by the same gear of the primary shaft. This arrangement, for the changing of the speeds, leads to having two output movement gears of the secondary shafts, called drive gears, which are different. This structural characteristic locks the transmission at all levels to a spacing or ratio between the first and fourth speed; and consequently, for the intermediate spacing between the first and second speed, between the second and third speed, and between the third and fourth speed.
In addition, none of these known transmissions makes it possible to have a synchronized reverse of a small size (standard reverse, i.e., with a sliding gear).